[linux-dvb] Re: [OT] Reality

[Andrew de Quincey <adq_dvb@lidskialf.net>]

On Saturday 15 May 2004 23:42, you wrote:
> From: "Gavin Hamill" <gdh@acentral.co.uk>
>
> > I'm not sure what DVB-SI is
> > (is the one pertaining to CAMs and encryption?)
>
> No, DVB-SI is "DVB Service Information". Look at it this way: MPEG-2
> defines the _base_ of a digital television system, but leaves many things
> open, e.g. how to transmit network-specific reception information, service
> names, etc.
>
> Thus, DVB-SI is what "completes" MPEG-2 to a full digital television
> system, DVB. ATSC is a different "completion" of MPEG-2 and uses different
> data formats for service information. I think the main difference is that
> DVB-SI uses the same table and descriptor format that MPEG-2 uses, while
> ATSC uses fixed-size tables, which are easier to parse, but are not
> consistent with the MPEG-2 base.
>
> > It's interesting to note that the reason we dropped from using QAM64 /
> > FEC2_3 was to 'improve the picture quality' (reduce UNCs in fringe
> > areas) but the lower available bitrate means each station is now
> > transmitting a lower quality picture. Again, so much for progress...
>
> Oh, so there's no more QAM64 DVB-T in the UK? Hmm, I think it will _have
> to_ return some day, because HDTV is very bandwidth hungry :-)

Only some channels are QAM-16. The "ITV" transponders are still QAM-64. My 
guess for HDTV is they're relying on the transition to all-digital thus 
freeing up the currentl analogue frequencies.

http://www.dtg.org.uk/retailer/dtt_channels.htm


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